Researches On Physical Layer Network Coding Detection And Channel Estimation

Network coding theory is an important breakthrough in the field of information theory in theearly21st century, which can improve network throughput, to increase the robustness of the systemand to improve network load balancing. Broadcast property of the wireless network can provide agood application environment for the network coding, therefore, the physical layer network codingtechnology become a hot research topic in recent years. The result of research shows that networkcoding can not only improve the capacity of the network, but also can improve the bandwidthutilization and network security, while saving energy consumption of nodes in the network. Afterintroducing the wireless cooperative communication and network, coding techniques, this thesismainly focuses on detection technique and channel estimation technique of the network codingtransmission scheme in the two-way wireless relay networks, Compared with the traditionalcollaborative communication technology, such as Amplify and Forward(AF) and Decode andForward(DF), this scheme can spend less time slots to complete the exchange of information. LSchannel estimation techniques can be used to obtain channel information parameters which used inthe detectors of receivers to recover the original signal.Aiming to the three-slot network coding scheme, the first work of this thesis studies how to usesoft decision to replace hard decision and calculate the approximate log-likelihood ratio of the XORsignal at ther receiver of the relay. Next, after studying the two-source LS channel estimationscheme, the application of this scheme in the AF based cooperative relaying is evaluated. In the lastwork of this thesis, we continue to apply the joint channel estimation of two singles into three-slotand DF based network coding scheme, which can reduce the estimated calculation time occupiedand the simulation results show that the scheme can gain a more accurate link coefficients.